[Tux3] Another modest code drop
shapor at gmail.com
Sat Aug 2 06:15:56 PDT 2008
On Wed, Jul 30, 2008 at 9:46 PM, Daniel Phillips <phillips at phunq.net> wrote:
> The split.c code is now generally better, and actually runs the test
> case correctly, which the previous version did not.
> Turning the groups vector upside down like the entries vector made
> things considerably more regular. The leaf_insert function is now
> pretty readable, which is something of an achievement given all the
> corner case in it.
> One neat thing about this insert is, there is only one memmove on
> the fast path, and that one usually moves zero bytes. Otherwise as
> can be seen, the fast path is very fast.
32 * The top level index is a table of groups of entries all having the same
33 * high 24 bits of logical address which is only stored once, along with the
34 * 8 bit count of entries in the group. Since there can be more than 256
35 * entries at the same logical address, there could be more than one group
36 * with the same logical address (not handled yet, which limits the number of
37 * different versions in the leaf to 256).
I might be missing something here, but it looks like its worse than
that. Since you don't handle more than one group with the same loghi,
if a group has more than 255 entries, the count simply loops and you
start corrupting the leaf. The attached test illustrates the issue.
-------------- next part --------------
A non-text attachment was scrubbed...
Size: 638 bytes
Desc: not available
More information about the Tux3